The present invention relates generally to tools and more particularly to a battery powered tool for driving screws, the battery powered tool including a screw starting device.
Manually tightening screws is a slow, time consuming procedure that is very tiring to a person""s hand and arm. It is well known that the torque or force which must be applied to a screw can vary substantially as the screw is advanced into anchoring engagement with an associated surface. A battery powered screwdriver is a typical tool for applying this torque to a screw to complete the engagement of the screw with the associated surface. Battery powered screwdrivers typically do not have the high-torque capability necessary to complete the engagement process available from a conventional screwdriver. The present invention combines in a single tool, the high speed effortless drive capability of a battery powered screwdriver with the high torque feature of a manual screwdriver required to set screws.
According to one aspect, the invention provides a battery powered screwdriver with a high torque feature.
A further aspect of this invention is to provide a battery powered screwdriver using an alkaline battery pack enabling the screwdriver to be stored for an extended period of time with retained battery life.
A further aspect of this invention is to employ a locking device which upon being activated causes the battery operated screwdriver to operate as a manual screwdriver.
A further aspect of this invention is to provide a device for setting a screw, with which a screw can be readily and reliably attached to the tip end of a battery operated screw driver.
In one embodiment, the present invention provides for a hand-held power tool comprising a housing having a member disposed therein and a spindle for receipt of a tool bit wherein the spindle is retained on a shaft The spindle and shaft define an axis of rotation relative to the housing. The power tool further comprises a collet having a sleeve that includes a collet engaging portion disposed on an inner surface of the sleeve and an opening centered on the axis for passage of the shaft therethrough and for receiving the member disposed in said housing to permit axial sliding movement between a locked position and an unlocked position. The power tool further comprises a spindle engaging portion disposed on the spindle wherein the spindle engaging portion engages with the collet portion means when the collet is moved in the locked position thereby rigidly locking the collet and the spindle together to prevent rotational movement of the spindle. The tool of claim 1, wherein the rigidly locking of the collet and the spindle permits operation of the power tool in a manual mode in which rotational forces applied to the housing are directly transmitted to the spindle and tool bit therein. Optionally, the opening in the collet has a non-circular cross-section and the member has a matching non-circular cross-section thereby preventing rotation of the collet about the axis with respect to the housing in either the locked or unlocked positions. The collet may further comprise exposed means for urging the collet in the locked position such as a pair of ears that extend from an outer surface of the collet. Preferably, the spindle engaging portion comprises a plurality of teeth extending axially from the spindle thereby forming a plurality of recesses therebetween and wherein collet engaging portion comprises a plurality of teeth extending radially from the inner surface of the sleeve thereby forming a plurality of recesses therebetween, said plurality of teeth on the spindle mesh with the plurality of recesses in the collet and said plurality of teeth in collet mesh with the plurality of recesses in the spindle to create a rigid locking engagement between the collet and the spindle thereby preventing rotation of the spindle in the locked position.
In another embodiment, the present invention provides for a spindle locking device for use in a hand-held power tool wherein the hand-held power tool includes a housing having a member disposed therein, a shaft, and a spindle mounted on the shaft, the spindle locking device comprising a collet having a sleeve that includes a longitudinal axis and an inner surface. The sleeve includes collet engaging means disposed radially on the inner surface thereof. Further, the sleeve defines an opening centered on the axis for passage of the shaft therethrough and for receiving the member disposed in said housing to permit axial sliding movement of the collet relative to the member between a locked position and an unlocked position. The spindle locking device further comprises spindle engaging means disposed on the spindle wherein the spindle engaging means mesh with the collet engaging means when the collet is moved in the locked position thereby rigidly locking the collet and the spindle to prevent rotational movement of the spindle.
In another embodiment, the present invention provides for a spindle locking device for use in a hand-held power tool wherein the hand-held power tool includes a housing having a member disposed therein, a shaft defining an axis of rotation, and a spindle coaxially mounted on the shaft for receipt of a tool bit therein, the spindle locking device comprising a collet having a body including a longitudinal axis, a proximal portion and a distal portion. The body includes a radial wall disposed between the proximal and distal portions of the body wherein the wall has an inner surface facing the proximal portion and an outer surface facing the distal portion. The wall further includes collet engaging means that extend axially from the outer surface of the wall, and a sleeve extending axially from the inner surface of the wall defining an opening centered on the axis for passage of the shaft therethrough and for receiving the member disposed in said housing to permit axial sliding movement between a locked position and an unlocked position. The spindle locking device further comprises spindle engaging means disposed on the spindle wherein the spindle engaging means mesh with the collet engaging means when the collet is moved in the locked position thereby rigidly locking the collet and the spindle to prevent rotational movement of the spindle. Preferably, the collet body is conically shaped. Preferably, the spindle engaging means comprise a plurality of teeth extending axially from the spindle thereby forming recesses therebetween and wherein collet engaging means comprises a plurality of teeth extending axially from said outer surface of the wall thereby forming recesses therebetween, said plurality of teeth on the spindle mesh with the pluraility of recesses in the collet and said plurality of teeth in collet mesh with the plurality of recesses in the spindle to create a rigid locking engagement between the collet and the spindle thereby preventing rotation of the spindle in the locked position.
In an alternative embodiment, the present invention provides for a screw starter device for use alone or in combination with the screwdriver according to the present invention. The screw starter device temporarily holds a screw while starting it into a substrate. The screw starter device comprises a tubular member defined by a proximal end portion, a distal end portion and a central body portion. An arcuate opening large enough to admit the head of a screw is positioned in the side of the body portion. A first longitudinal slot large enough to admit the shank of the screw extends through the side of the body portion towards the distal end. A latitudinal slot positions the head of a screw and is located on the body portion opposite the arcuate opening. A second longitudinal slot is located on the body portion opposite the first longitudinal slot. The inside surfaces engage and hold the screw in the screw holder and release the screw once the advancement of the screw is completed. Preferably, the screw holder device is consturced of a plastic material such that the distal end of the screw starter device can expand and allow the screw to be released once the advancement of the screw is completed. The distal end will elastically return to its original state, ready to accept another screw, once the screw is released.